"1 in 1000 male births
1 in 3000 females are carriers
Mutation of the fragile X mental retardation (FMR1) gene on the X chromosome.
Results in failure to express the fragile X mental retardation protein (FMRP).Required for normal neural development.
Most widespread single-gene cause of autism and inherited cause of intellectual disability.
The gene is found at the end of the Xchromosome and shows as a �fragile� site on the chromosome � it looks
as though it is breaking off but is not quite separated."